This application claims the priority of German application 197 33 191.2, filed in Germany on Jul. 31, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a cross member for vehicles which is formed as an extruded hollow profile.
A vehicle frame is known from German Patent Document DE 195 17 918 A1 which comprises a side member as well as a cross member which is connected with the side member at the forward end of the side member. The cross member has a connection flange which extends along the cross-sectional height of the side member and which is welded to the side member on one side. On the side of the connection flange situated opposite the side member, the cross member is supported along a cross-sectional area at the connection flange, this cross-sectional area having a lower height than the side member. In the event of a deformation, the connection flange will deform first and, because of its small cross-sectional area on the connection flange, the side member will first penetrate against a slight resistance into the side member. A deformation of the cross member is not disclosed.
With respect to the above, it is an object of the invention to provide a cross member which, in the event of a deformation, has a controlled deformation behavior while simultaneously the energy absorption is good.
According to the invention, this object is achieved by providing a cross member formed as an extruded hollow profile, wherein the cross member has at least two impact surfaces and the impact surfaces are supported by way of webs arranged in pairs of respective interior and exterior webs with respect to the remaining cross-section of the cross member, the interior and exterior webs assigned to each impact surface being inclined in the same direction diagonally with respect to a predetermined impact direction, and wherein the setting direction for the different impact surfaces are selected to extend in opposite diagonal directions.
According to the invention, it is suggested to provide at least two impact surfaces on the cross member and to support the impact surfaces with respect to the remaining cross-section of the cross member by means of webs arranged in pairs. The webs assigned to one impact surface are in each case set in the same direction diagonally with respect to an impact direction. In contrast, the setting directions for different impact surfaces are selected in the opposite direction. As a result, a first cross-sectional area of the cross member constructed in this manner has a comparatively soft construction and, without the forming of any force peaks, initiates the deformation of the cross member. It is a special advantage in this case that, because of the webs arranged in pairs and set diagonally, the impact surfaces carry out a movement transversely to the impact direction.
Since the webs are set in opposite directions on different impact surfaces, a movement of the impact surfaces also takes place in different directions so that the impact surface as a whole is enlarged in the course of an impact induced deformation event. This also increases the moment of resistance transversely to the impact direction so that an escaping of the cross member transversely to the impact direction can be prevented. It is also a special advantage that, because of the transverse movement of the impact surfaces, the surrounding areas are deformed and thus, in the event of an impact, a reduction of the impact energy is achieved not only by deformations in the longitudinal direction but, in addition, by deformations in transverse directions so that, on the whole, the impact energy can be reduced with a lower longitudinal deformation.
For the construction of the first cross-sectional area in certain preferred embodiments, it is further suggested to construct this area such that the diagonally set webs are arranged on longitudinal sides of the impact surfaces. In this case, the bases of those webs which originate from mutually opposite longitudinal sides of the impact surfaces are connected with one another. This geometrical shape can be achieved in a particularly advantageous manner in that an impact surface first constructed in one piece is provided approximately in the center with a flute in the longitudinal direction of the cross member. This flute may be constructed, for example, in a V-shape or a U-shape.
For constructing the cross member, it is further suggested according to certain preferred embodiments to provide a second cross-sectional area adjoining the above-described first cross-sectional area, which second cross-sectional area has a stiffer construction in the deforming direction than the first cross-sectional area. Preferably, the lateral walls of the second cross-sectional area are constructed as continuations of the exterior webs of the first cross-sectional area. In addition, a center web is provided which originates from the connected bases of the interior webs. This second cross-sectional area has the task of reducing impact energy by deformation during the deformation process after the deformation path of the first cross-sectional area is exhausted. As a result of the fact that the second cross-sectional area is constructed as a continuation of the first cross-sectional area, force peaks can be securely avoided.
Finally, it is suggested according to certain preferred embodiments to provide a third cross-sectional area adjoining the second cross-sectional area, which third cross-sectional area has a stiffer construction than the second cross-sectional area. This third cross-sectional area has the task of ensuring the basic stiffness of the cross member so that the forces occurring at the cross member during the deformation of the first and of the second cross-sectional area can be introduced into the adjoining support structure of the vehicle, for example, the side members. This third cross-sectional area therefore has such a stiff construction that it is significantly deformed neither during the deformation of the first and of the second cross-sectional area, nor during the further introduction of force immediately following.
It should particularly be pointed out that the advantageous construction of the first cross-sectional area can also be combined with arbitrary second cross-sectional areas (if no third cross-sectional area is provided) or with arbitrary second and third cross-sectional areas.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.